Flow pattern enhancer system for gas wells with liquid load problems

ABSTRACT

A flow pattern enhancer system mainly for gas-producing oil wells with liquid load problems, comprising mechanical elements that atomize the liquids accumulated at the bottom of the well facilitating their transport to the surface, by decreasing frictional pressure drops and weight of the hydrostatic column.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit under 35 U.S.C. §119 of MexicanPatent Application No. MX/a/2011/008907, filed Aug. 24, 2011, which ishereby incorporated by reference in its entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a flow pattern enhancer system mainlyuseful in gas-producing oil wells with liquid load problems, comprisingmechanical elements for atomizing the liquids accumulated at the bottomof the well, and facilitating its transport to surface, caused by thedecrease of the frictional pressure drop and weight of the hydrostaticcolumn.

BACKGROUND OF THE INVENTION

The accumulation of liquids in the gas wells occurs naturally becausethe decrease of deposit energy during their productive lives, caused bythe decrease of the deposit pressure and thus the expenditure producedby the well. While the production expenditure is maintained above thecritical expenditure, the liquids will be carried to the surface andwon't be accumulated at the bottom of the well.

The liquid load in a gas well is also related to the change of flowtype, the big pressure drops through the production pipes are caused byfluctuations in the gas and liquid transport, being normally calledthese fluctuations potholes. The distribution of the liquid and gasphases simultaneously flowing through a piping, may be classified by itsform and rate and are called flow patterns.

The parameters affecting in the formation of the liquid load in a gaswell are the following:

Static pressure of the deposit.

Pressure at the wellhead.

Pressure at the discharge line.

Diameter of the production pipe.

In Mexico, in order to solve the gas deposit exploitation issues withliquid load problems, at present liquid recovery systems are applied,allowing the extraction of the liquids of the bottom of the wells. Itscorrect selection will depend mainly of the well characteristics,although all are aimed to solve the same problem, they don't work underthe same conditions; generally, the artificial systems of productionhave a technical and temporary range therefore always be sought the oneworking longer, optimally and at lower cost, without being this animpediment to use different systems during the productive life of thewell.

The state of the art in solving the gas deposits exploitation issueswith liquid load problems, mainly reports the following technologies:

Small Tubing

Small tubing is a piping of smaller diameter than the production piping,this is introduced in the well in order to reduce the flow area formaintaining the expenditure above the critical value. Good yields havebeen observed in wells with low production volume, in which thefrictional losses are not very significant.

The leading disadvantage of this system, besides an unstable production,is that it stops working optimally in a short time, so if it is notcombined with other system, it is only a temporary solution.

Foaming Agents/Reactive Liquids

Both methods consist on the introduction of surfactants or foamingagents in the well to reduce the surface tension of the fluids and formfoams. When this happens, the liquid column becomes foam, becominglighter and facilitating its transport to the surface; however, in spiteof obtaining good result for water, in case of the condensates it hasbeen difficult to obtain a substance to make them foamy, so this is thereason why it is not convenient to apply this system in wells with watercut below 80%.

This system is mainly used in wells with a very low expenditure ofproduction due to the hanging and the high pressure drops along thepiping, however it is not advisable to use in wells with problems ofemulsified liquids because the investment in the surfactant products maybe small compared to the necessary for the products breaking theemulsions formed. The introduction of foaming bars is performed throughthe Production tubing (TP) and the reagents are injected by a capillarytubing, the can be injected in the zone of triggers or at the end of theTP.

Plunger Lift

Used mainly in wells with intermittent production, the plunger liftgenerates a mechanical interface between gas and liquid. At thebeginning, the well is closed and the plunger is on the surface droppingit inside the TP, in its way down, the plunger allows the pass of liquidabove it preventing its return; once at the bottom the pressuregenerated by the gas under the plunger is increased until it matches thepressure of the motor valve opening of the well located on the surface.Once the well is opened, the plunger travels along the production tubingdisplacing the liquid pothole; afterwards the well is closed (byindication of the motor valve) and the plunger falls to the bottom tostart again the cycle. During its travel, this plunger is touchinginternally the tubing freeing it of paraffins, salts, carbonates, etc.,that may deposit in the interior of the same.

It is important for this system that the well produces its fluids with arelation gas-oil (RGA) and pressure enough to lift the potholes ofliquid; for the case of pipe sizes, this system can work with big sizes,being this a disadvantage in the other systems.

Compressors Installed at the Mouth of the Well (Compressors)

The compression increases the gas velocity to be equal or greater thanthe critical velocity and at the same time decreases the pressureflowing in the wellhead causing the pressure in the side of the depositnear the well to decrease as well and extends the life of the well.

There are many types of compressors varying according to the initialinvestment, operating costs and functionality of each particular well.

Hydraulic Pumping

In this system, energy is transmitted from a motor fluid to the fluidscontained in the well for its extraction; a pump on the surfacetransmits dynamic energy to the motor fluid introduced in the well,wherein it mixes with the fluids therein and by a pump at the bottom,this mixture is impelled to the surface where it enters to a separatorsending the well fluids out of the system and the motor fluid again tothe pump on the surface.

This system does not present a depth limit for its application and it isapplicable in deviated wells.

For gas wells, the pump located at the bottom must be Jet type becausethe reciprocating pump doesn't admit gas and has to open a line to ventit. The jet type pumps reduce the pressure in the side of the Formationincreasing the velocity of the fluid introduced in them.

Gas Lift

In this system, gas is injected to the well to a certain depth. The gasis mixed with the liquid column making it lighter, due to this, itspressure at the bottom is reduce, causing the pressure from the depositto be enough to push the column to the surface.

Although it is not achieved to reduce the pressure at the bottom of thewell as with other pumping systems, the gas lift is outstanding becauseof its versatility and due to this is a good candidate in certainconditions. While other pumping systems become inefficient for highvalues of the gas-liquid relation (RGL), in this case a big amount ofgas from the deposit will directly decrease the volume of gas to beinjected; it has no trouble handling solids and can be used in deviatedwells although as these become more horizontal, the gas injectiondoesn't reduce the weight of the liquid column and may increase thefrictional pressure losses.

Progressive Cavity Pumps

This system consists mainly of a stator with internal helical form,double entrance and a helical rotor rotating in the stator. The crosssection of the rotor is circular and at every point eccentric to theaxis; the centers of the sections are supported along a helix, whichaxis is the rotor axis. Both are linked such that the section of therotor has a reciprocating movement through the duct of the stator. Thismovement causes cavities that be formed, which are delimited by a lineadjustment between the two elements. When the rotor makes a turn, saidcavities arranged in a helical form move, including the liquid to becarried, being independent said cavity from the next one to be form bythe adjustment line, therefore avoiding the return of the liquid.

Although this system was designed originally to carry solids and viscousfluids, it has also been used for liquid extraction in gas wells; itsapplicability is reduced mainly to the following general conditions:

Depths of no more than about 1,250 meters

Relatively high liquid expenditures

Low pumping profile

Low temperatures in the well.

Automated System of Liquid Recovery for Wells Producing Gas andCondensate

It is based on the installation of a small tubing or flexible piping andof a valve control system automated on the surface. The target of thissystem is to “sweep” the accumulated liquid through a flexible piping(or small tubing) and to produce gas through the production piping; thecontrol valves, registering a pressure differential, act opening andclosing the system, so the fluids can be produced continuously and thusavoid the intermittent production of the wells or its definitiveclosure.

SUMMARY OF THE INVENTION

The present invention is an improvement over the above mentionedtechnologies, since it relates integrally to the operation principle ofa flow pattern enhancer system for use mainly in gas-producing oil wellswith problems of liquid load and takes advantage of the deposit energyand its fluids in order to induce a change in the characteristics of theflow pattern of the liquid and gas phases from the bottom of the well,enhancing the transport of liquid through the production piping toreduce the pressure drops in the latter.

Therefore, an object of the present invention is to provide an enhancersystem for the flow pattern of gas wells with liquid load problems,comprising mechanical elements atomizing the liquids accumulated at thebottom of the well, facilitating its transport to the surface bydecrease of frictional pressure drops and weight of the hydrostaticcolumn.

A further object of the present invention is to provide a flow patternenhancer system which is used mainly in gas-producing oil wells withliquid load problems.

Yet another object of the present invention is to provide a flow patternenhancer system located on the lower extremity of the production pipingof the gas producing wells with liquid load problems, to displace to thesurface the liquids accumulated at the bottom of the well.

The flow pattern enhancer system of the present invention is mainly usedin gas wells with liquid load problems, and comprises the followingelements:

a) primary expander,

b) homogenization chamber,

c) secondary expander,

d) suction veins, and

e) anchorage and tightness system,

for displacing the liquids accumulated at the bottom of the well to thesurface, taking advantage of the same energy of the gas produced,extending the flowing life of the wells in a continuous form andincreasing its recovery factor.

The primary expander has a smaller inner diameter than thehomogenization chamber, and is connected to the lower part of thehomogenization chamber. The homogenization chamber is positioned betweenthe primary expander and the secondary expander, with the primaryexpander below and the secondary expander above, i.e., its lower part isconnected to the primary expander and its upper portion is connected tothe secondary expander.

The secondary expander is located above and attached to the homogenationchamber. The secondary expander houses the suction veins, and the upperportion of the secondary expander has a fishing neck. The suction veinsare housed in low pressure zones inside the secondary expander andcommunicate the low pressure zones inside the secondary expander withthe liquid accumulated outside the system. The anchorage and tightnesssystems are coupled in the inside to the primary expander andhomogenization chamber and on the upper extreme to the secondaryexpander.

The anchorage and tightness system enables installation of the flowpattern enhancer system at any depth of the production piping of thewell. The anchorage and tightness system forces the flow to take placeonly inside the flow pattern enhancer system. The flow pattern enhancersystem has mechanical anchors which are attached to the piping andelastomeric seals which allow the system to anchor and seal the insidein order to confine the flow completely inside the system.

The flow pattern enhancer system is installed in the lower extremity ofthe production piping. Thus, the flow pattern enhancer system can beplaced below the depth to which bubbling pressure is present. Employmentof the flow pattern enhancer system enables increase of the gas velocityto 4-6 m/s, achieving fog flow and a continuous flow structure withliquid droplets dispersed in the continuous gas phase.

When designing the present flow pattern enhancer system, each elementdepends on three different processes, namely expansion, compression andmixing, and are performed by specific methods consisting primarily ondetermining the flow areas and geometries thereof. The drag coefficientis determined by the formula:

Drag coefficient=Driving flow/Dragged Flow.

The flow pattern enhancer system of the present invention increases gasproduction over 300% from the initial production and prevents formationof hydrates, thereby avoiding re-pressure of surface lines because ofmethane hydrate accumulation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows exterior and interior views of the enhancer system of theflow pattern of gas wells with problems of liquid load of the presentinvention.

FIG. 2 shows deformation of a liquid drop depending on the value ofWeber's number.

FIG. 3 shows the transition of flow type experienced by the gas in thewell as the gas velocity decreases.

FIG. 4 shows a diagram of the secondary expander of the presentinvention.

FIG. 5 shows the behavior of the pressure gradient and productions ofthe well Cuitlahuac-802 of Activo Integral Burgos, with and without theuse of the enhancer system of the flow pattern of gas wells with liquidload problems of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a flow pattern enhancer system usefulmainly in gas-producing oil wells with liquid load problems, comprisingmechanical elements atomizing the liquids accumulated at the bottom ofthe well, thereby facilitating their transport to the surface, bydecrease of the frictional pressure drops and weight of the hydrostaticcolumn.

FIG. 1 shows exterior and interior views of the enhancer system of theflow pattern applied mainly in gas-producing oil wells with liquid loadproblems of the present invention, which comprises five mechanicalelements (subsystems):

1) Primary expander. It is the first mechanical element, it allows theexpansion of the gas stream from the well that is the driving fluid to astate of high speed; that is, it has the function of causing the firstpressure drop through a controlled flow restriction, generating the gasexpansion from the well, driving the fluid to a state of high speed,caused by the pressure energy of the deposit. The sudden expansion ofgas increases the velocity that, in presence of liquid, promotes theformation of a homogenous mix.

2) Homogenization chamber. It is the second mechanical element and it isconnected to the primary expander, inside the stabilization andhomogenization of the liquid and gas flow from the first stage ofexpansion are performed, and the fluids are transported through thechamber to the third mechanical element called Secondary expander; thatis, it has a larger interior diameter than the Primary expander and itis connected to the Primary expander in the lower part and to theSecondary expander in the upper part, inside the stabilization andhomogenization of the liquid and gas flow from the first stage ofexpansion are performed, the fluids are transported through the chamberto the Secondary expander.

3) Secondary expander. It is the third mechanical element and it isattached to the homogenization chamber, having the function of provokinga second restriction to flow, it has such a geometry that it isincreases the gas velocity, forming zones of low pressure inside, whereit houses the Suction veins; in the upper part it has a fishing neck,which is the geometry allowing the installation and removal of theenhancer system of the flow pattern inside the production piping.

4) Suction veins. They are the fourth mechanical element; they arelocated in the low pressure zones of the interior of the Secondaryexpander and communicate the low pressure zones of the interior of theSecondary expander with the liquid accumulated outside the system; theyhave the function of allowing the liquid accumulated outside the systemto be suctioned by the gas stream (driving fluid) decreasing theparticle size of the liquid (atomization process) using the highvelocity of the gas stream achieved in the Secondary expander in the lowpressure zones.

5) Anchorage and tightness system. It is the fifth mechanical element;it is attached to the primary expander and homogenization chamber on itslower part, and to the secondary expander on its upper part; and itallows to install the enhancer system of the flow pattern at any depthof the production piping of the well and at the same time, it forces theflow to take place only on the inside of all the above-mentionedelements; it has mechanical anchors which are attached to the piping andelastomeric seals allowing the system to anchor and cause tightnessoutside so that the flow performs completely as mentioned above.

According to the foregoing, the enhancer system of the flow pattern ofgas wells with liquid load problems of the present invention, isinstalled in the lower extreme of the production piping and has thefunction of causing an increase in the fluid velocity by passing by tworestrictions inside the system. It causes expansion of gas flowing alongthe condensates and/or water. The process allows obtaining a uniformmixture of gas/condensates/water (liquid atomization in the gas), whichprevents slippage of gas and pitch problems. Besides it maintains aminimum counter-pressure over the side of formation and reduces thefrictional pressure drops.

The enhancer system of flow pattern of the present invention can beplaced below the depth to which it has the bubbling pressure and it isuseful when you are managing high ratios of dissolved/gas/oil, as inthis case the additional amount of released gas helps to “drag” theliquids accumulated at the bottom of the well to the surface, withoutthe requirement of an external energy source.

The flow pattern enhancer system of the present invention uses thelatent energy in the dissolved gas, by releasing and expanding to liftthe fluids accumulated in the well; when the gas velocity is lower thanthe minimum drag velocity, there will be liquid runoff at the bottom ofthe well through the walls of the production piping. When this occurs,the liquids are reincorporated to the gas stream at high velocity whenthey are introduced to the body of the secondary expander via suctionveins, that is, low pressure zones which in turn fractionated,distribute and atomize the liquids in the gas stream.

The enhancer system of the flow pattern of the present invention isbased on the principle of conservation of momentum of the streams ofinvolved fluids (gas, condensed hydrocarbons and/or water). The flowpattern enhancer system of the present invention is based on thetransmission of impact energy of a fluid at high velocity (gas), againstanother fluid in motion or at rest (condensates and/or water), toprovide a fluid mixture at a moderately high velocity, that decreasesuntil a final pressure greater than the initial of the lower velocityfluid is obtained.

The whole flow pattern enhancer system of the present invention promotesthe gas expansion at the bottom of the well, increasing the velocity towhat is needed in order to incorporate the existing liquids in atomizedform through the production piping to the surface. Such velocity istermed “critical velocity”. On this regimen the liquid drops move insidethe gas stream being subjected to the gravity and drag forces,fragmenting the liquid particles by the effects of incorporation throughthe suction veins and secondary expander, while the superficial tensionof the liquid acts to avoid its fragmentation (surface pressure). Theantagonism of the two pressures determines the maximum measure that adrop can achieve, being represented as:

-   -   Velocity pressure: ν_(G) ² ρ_(G)    -   Surface pressure: σ/d        where:

-   ν_(G): velocity at which the drop of liquid is displaced in the gas

-   ρ: density of the gas

-   σ: surface tension of the drop of liquid

-   d: diameter of the drop of liquid

These two pressures make up the Weber's (We), which is a dimensionlessnumber useful on the analysis of flows wherein there is a surfacebetween two different fluids.

$\begin{matrix}{{We} = \frac{v_{G}^{2}\rho_{G}d}{\sigma \; g_{c}}} & (1)\end{matrix}$

If this number exceeds the critical value, the drop of liquid will befragmented, the critical value for the free fall of a drop is between 20and 30.

With a Weber's number within the critical range, the deformation ofdrops of the liquid at high velocities of the gas stream is considered aspherical shape; if the Weber's number is under 20 or above 30, therewill be a pressure difference at the sides of the liquid drop causing itto deform, which is clearly seen in FIG. 2.

The total gravity force is represented by the following equation:

$\begin{matrix}{F_{g} = {\frac{g}{g_{c}}\left( {\rho_{L} - \rho_{G}} \right) \times \frac{\pi \; d^{3}}{6}}} & (2)\end{matrix}$

and the total drag force is given by:

$\begin{matrix}{F_{d} = {\frac{1}{2g_{c}}\rho_{G}C_{a}{A\left( {v_{G} - v_{L}} \right)}^{2}}} & (3)\end{matrix}$

where:

-   g: gravitational constant-   d: diameter of the drop of liquid-   ρ_(L): density of liquid-   ρ_(G): density of gas-   C_(a): drag coefficient-   A: cross-sectional area of the drop of liquid-   ν_(G): velocity of gas-   ν_(L): velocity of drop of liquid

The critical velocity of gas for transporting the drop of liquid of thewell bottom is defined as the velocity at which the drop will besuspended in the gas stream. Therefore, the critical velocity of gasν_(G) is the velocity at which ν_(L)=0, if the velocity of the drop ofliquid is zero, the net force on it is zero. The equation defining thisconcept of critical velocity is the following:

F_(g)=F_(d)   (4)

Substituting both forces values:

$\begin{matrix}{{\frac{g}{g_{c}}\left( {\rho_{L} - \rho_{G}} \right) \times \frac{\pi \; d^{3}}{6}} = {\frac{1}{2\; g_{c}}\rho_{G}C_{a}{Av}_{C}^{2}}} & (5)\end{matrix}$

Rewriting the area A=πd²/4 and solving for ν_(C):

$\begin{matrix}{v_{C} = \sqrt{\frac{4{g\left( {\rho_{L} - \rho_{G}} \right)}d}{\beta \; p_{G}C_{H}}}} & (6)\end{matrix}$

This equation considers known a liquid drop diameter. Actually, theliquid drop diameter depends on the gas velocity, but the Weber's numbercan be obtained.

When Weber's number is 30, substituting ν_(G) for ν_(C) and clearing d:

$\begin{matrix}{d = {30\frac{\sigma \; g_{c}}{\rho_{g}v_{C}^{2}}}} & (7)\end{matrix}$

Substituting this equation on Equation 6:

$\begin{matrix}{{v_{C} = {\sqrt{\frac{4}{3}\frac{\left( {\rho_{L} - \rho_{G}} \right)}{\rho_{G}}}\frac{\beta}{C_{a}}30\frac{\rho \; g_{c}}{\rho_{G}v_{C}^{2}}}}{or}} & (8) \\{v_{C} = {\left( \frac{40\; g\; g_{c}}{C_{a}} \right)^{1\text{/}4}\left( {\frac{\rho_{L} - \rho_{G}}{\rho_{G}^{2}}\sigma} \right)^{1\text{/}4}}} & (9)\end{matrix}$

Considering a drag coefficient C_(a) of 0.44, which corresponds to thevalue used for a completely turbulent flow. Substituting the dragcoefficient for turbulent flow and the g and gc values we have:

$\begin{matrix}{v_{C} = {17.514\left( {\frac{\rho_{L} - \rho_{G}}{\rho_{G}^{2}}\sigma} \right)^{1\text{/}4}}} & (10)\end{matrix}$

where:

-   ρ_(L): liquid density (lb_(m)/ft³)-   ρ_(G): gas density (lb_(m)/ft³)-   σ: surface tension (lb_(f)/ft)-   ν_(C): critical velocity of gas (ft/s)

If using the surface tension in dyne/cm units is desired, by using theconversion (lb_(f)/ft)=0.00006852(dyne/cm) it is obtained:

$\begin{matrix}{v_{C} = {1.593\left( {\frac{\rho_{L} - \rho_{G}}{\rho_{g}^{2}}\sigma} \right)^{1\text{/}4}}} & (11)\end{matrix}$

where all the variables keep the units of Equation 10 but σ.

Once the critical gas velocity is known, the critical expenditure can becalculated that is a more practical value for its applicability:

$\begin{matrix}{q_{C} = \frac{3.067\; {pv}_{C}A}{\left( {T + 460} \right)g}} & (12)\end{matrix}$

where:

-   A: cross-sectional area of the inside of the production piping (ft²)-   P: pressure on the wellhead (lb/pg²)-   T: temperature in the wellhead (° F.)-   q_(C): critical expenditure of gas (mmft³/day)

The predictions of critical velocity of wells with low pressures in thewellhead are more uncertain.

There are two versions of correlations, one for water and one forcondensed hydrocarbons:

$\begin{matrix}{v_{g,{water}} = \frac{5.62\left( {67 - {0.0031\; p}} \right)^{1\text{/}4}}{\left( {0.0031\; p} \right)^{1\text{/}2}}} & (13) \\{v_{g,{{condensed}\mspace{14mu} {hcns}}} = \frac{4.02\left( {45 - {0.0031\; p}} \right)^{1\text{/}4}}{\left( {0.0031\; p} \right)^{1\text{/}2}}} & (14)\end{matrix}$

where:

-   p: flowing pressure in the wellhead (lb/pg²)-   ν_(g): critical gas velocity (ft/s).

The coefficients 5.321 and 4.043 can be considered respectively forwater and hydrocarbons besides the correlation of critical velocity,obtaining the critical gas expenditure as follows:

$\begin{matrix}{q_{C,{{gas} + {water}}} = {\frac{0.0676\; {pdt}_{t}^{2}}{\left( {T + 460} \right)z}\frac{\left( {45 - {0.0031\; p}} \right)^{1\text{/}4}}{\left( {0.0031\; p} \right)^{1\text{/}2}}}} & (15) \\{q_{C,{{gas} + {{condensed}\mspace{14mu} {hcs}}}} = {\frac{0.0890\; {pdt}_{t}^{2}}{\left( {T + 460} \right)z}\frac{\left( {67 - {0.0031\; p}} \right)^{1\text{/}4}}{\left( {0.0031\; p} \right)^{1\text{/}2}}}} & (16)\end{matrix}$

While the expenditure of fluids in a well is above the criticalexpenditure, there won't be a formation of liquid column at the bottomof the well.

FIG. 3 shows the transition of a flow type that a gas in the wellexperiences as the gas velocity decreases.

Based on the above, it can be established that the flow pattern enhancersystem of the present invention increases the gas velocity promoting theliquid atomization, with a flow velocity relatively high of 4-6 m/s,achieving fog flow and a continuous flow structure (in the continuousgas phase there are liquid drops dispersed). The gas expenditure isenough to lift the liquid (water and condensate) to the surface. If theliquid drops flow in the same direction of gas, there is a mist flowstructure and if the liquid drops have a turbulent flow, it can becalled foaming or atomized structure.

The secondary expander showed on FIG. 4, includes the entrance sectionof the liquid stream; in this chamber it is dragged by the driving fluid(high velocity gas). The mixing chamber allows the intimate mixingbetween the driving and dragged fluids.

The design calculations consider three different processes: expansion,compression and mixing, so there are specific methods for each type ofelement, consisting primarily on determining the flow areas and itsgeometry. Once the equipment is designed, it must operate at steadystate conditions for which it was designed and the fundamentalcalculation is the drag coefficient:

Drag coefficient=Driving flow/Dragged flow

Based on the above, the enhancer system of flow pattern of gas wellswith liquid load problems of the present invention solves the problemscaused by the liquid accumulation at the bottom of wells, takingadvantage of the same energy of the gas produced to “sweep” theaccumulated liquid, so the fluids be produced in a continuous form andtherefore prevent the intermittent production of wells or its thedefinitive closure, extending the flowing life thereof and therebyincreasing the recovery factor reflected on the incorporation of gasreserves allowing the utilization of more energy resources.

The flow pattern enhancer system of the invention provides primarily thefollowing associated benefits:

a) Increases the recovery factor of well hydrocarbons, due to thereduction in the pressure requirement needed to administer the energy ofthe deposit;

b) Increases the lifting velocity of the produced fluids to a relativelyhigh flow velocity of gas of 4-6 m/s; the gas expansion flows along withthe condensed hydrocarbons and water, generating an uniform atomizedmixture with lower density, which reduces the pressure gradient flowingin the production piping;

c) Increases the gas production, as the well production is continuouswith a steady behavior even during the liquid discharge, it has aremarkable improvement in the flow pattern in the production piping bygenerating a homogenous dispersion of both phases;

d) Decreases the pressure drops along the production piping, as it isnot allowed that the liquid accumulates at the bottom of the well;

e) Preserves the deposit energy due to the increase of the bottompressure flowing;

f) Maintains the liquid production with a steady behavior caused by animprovement in the flow pattern of fluids along the production piping;and

g) Extends the flowing life of the wells as it preserves the energy inthe deposit by reducing the pressure drops along the production piping.

The following describes a practical example to have a betterunderstanding of the same, without limiting its scope.

EXAMPLE

The application of the enhancer system of flow pattern of gas wells withliquid load problems was made, in the well Cuitlahuac-802 of ActivoIntegral Burgos. In this well the liquid accumulation is a widespreadproblem at the Cuitlahuac field due to its conditions of pressure,production and compositions of the produced fluids.

The activities performed for the installation of the enhancer system ofpatter flow of the present invention consisted on:

1) Well selection: For the selection of the well, those wells havingenough information to perform a simulation of the behavior of the flowpattern enhancer are identified, and identify which did not haveinstalled another system obstructing the production piping.

2) Simulation of the production conditions of the well. The simulationwas performed based on a finite element, in order to determine theproduction conditions of the well and determine the optimum installationdepth, as well as the diameters of the flow restrictions, both upper andlower.

3) Design and manufacture of the enhancer system of flow pattern. Thesuitable enhancer system of flow patter for the conditions of pressure,temperature, depth and properties of the fluids produced by the well wasdesigned and manufactured.

Technical Specifications of the Enhancer System of Flow Pattern for theCuitlahuac-802 Well of Activo Integral Burgos:

a) Operating differential pressure of 7,000 psi.

b) Maximum working pressure of 11,000 psi.

c) Maximum operating temperature of 177° C. (350° F.)

d) Installed and released with steel line.

e) Interchangeable components and easy maintenance.

f) Generator interior of a tight seal for preventing leaks.

g) Maximum diameter of 2.250 inches.

h) Length of 2 meters.

i) System applicable to wells deviated up to 35° (3° for each 100meters).

j) Withstand harsh environments, with CO₂ and H₂S presence.

k) Primary expander, homogenization chamber and secondary expandermanufactured with steal 4140 treated with surface coating with ahardness of 97 RwC.

4) Installation of the enhancer system of flow pattern. The installationof the enhancer system of flow pattern was performed as follows:

The enhancer system of flow is installed on the production pipingextreme, it is introduced to the well through a steel line unit by adisgorging tool JDC called davit; after reaching the depth of placement,it anchors the production piping by sudden descendent movements with amechanical scissors and weight bars, the tightness of the system isobtained by hitting the upper part of the system with blind box. Theoperation sequence to recover the system is performed by hitting upwardswith mechanical scissors and weigh bars to release.

5) The pressure gradient behavior and productions of well Cuitlahuac 802of Activo Integral Burgos is shown in FIG. 5, which is supplemented withthe following results:

a) The enhancer system of flow pattern increased the gas production over300% compared to the initial production: from 0.315 to 1.08 millioncubic feet per day;

b) The well production is continuous and had a steady behavior evenduring the liquid discharge;

c) It had a remarkable improvement on the flow pattern in the productionpiping by generating a homogeneous dispersion of both phases, reducingthe water shear.

d) It reduced the pressure drops along the production piping (TP), as itwas not allowed that the liquid accumulate at the bottom of the well.

e) The deposit energy was preserved due to the increase of bottompressure flowing, as in the case of operation in the discharge line ofhigh pressure;

f) The anchorage operation of the enhancer system of flow pattern wasperformed successfully. The response of the well, monitored at thesurface with a phase measuring equipment, allowed to observe that thewell was stabilized with a gas production higher than normal, due to theapplication of enhancer system of flow pattern; likewise the liquidproduction had a more steady behavior, caused by an improvement in theflow pattern.

g) The enhancer system of the flow pattern can be used to extend theflowing life of the wells, as it preserves the deposit energy byreducing the pressure drops along the production piping, same as wasidentified by the register of flowing bottom pressure taken 2 hoursafter the installation.

h) It prevents the formation of hydrates, as it increases thetemperature in head to 45° C. (113° F.), due to the expansion andheating of gas caused by the enhancer system of flow pattern located at2,000 m.

i) Additionally, the enhancer system of flow pattern prevents there-pressure of surface lines because of the accumulation of methanehydrates, which reduce the flow area towards the battery, cause of lowgas production especially in winter.

1. A flow pattern enhancer system for gas wells, comprising thefollowing elements: a) primary expander, b) homogenization chamber, c)secondary expander, d) suction veins, and e) anchorage and tightnesssystem, for displacing the liquids accumulated at the bottom of the wellto the surface, taking advantage of the same energy of the gas produced,extending the flowing life of the wells in a continuous form andincreasing its recovery factor.
 2. The flow pattern enhancer system ofclaim 1, for gas-producing oil wells with liquid load problems.
 3. Theflow pattern enhancer system of claim 1, where the primary expander hasa smaller inner diameter than the homogenization chamber.
 4. The flowpattern enhancer system of claim 1, wherein the primary expander isconnected to the lower part of the homogenization chamber.
 5. The flowpattern enhancer system of claim 1, wherein the homogenization chamberis connected to the primary expander at the lower part and to thesecondary expander at the upper part.
 6. The flow pattern enhancersystem of claim 1, wherein the secondary expander is attached to thehomogenization chamber at the upper part of the homogenization chamber.7. The flow pattern enhancer system of claim 1, wherein the secondaryexpander houses suction veins.
 8. The flow pattern enhancer system ofclaim 1, wherein the secondary expander at the upper part has a fishingneck.
 9. The flow pattern enhancer system of claim 1, wherein saidsuction veins are housed in low pressure zones inside the secondaryexpander and communicate the low pressure zones inside the secondaryexpander with the liquid accumulated outside the system.
 10. The flowpattern enhancer system of claim 1, wherein anchorage and tightnesssystems are coupled in the inside to the primary expander andhomogenization chamber, and on the upper extreme to the secondaryexpander.
 11. The flow pattern enhancer system of claim 10, wherein saidanchorage and tightness system enables installation of the flow patternenhancer system at any depth of the production piping of the well. 12.The flow pattern enhancer system of claim 10, wherein the anchorage andtightness system forces the flow to take place only inside the flowpattern enhancer system.
 13. The flow pattern enhancer system of claim10, wherein the anchorage and tightness system has mechanical anchorswhich are attached to the piping and elastomeric seals which allow thesystem to anchor and seal the inside in order to perform completely theflow inside the system.
 14. The flow pattern enhancer system of claim 1,wherein the flow pattern enhancer system is installed in the lowerextreme of the production piping.
 15. The flow pattern enhancer systemof claim 1, wherein the flow pattern enhancer system can be placed belowthe depth to which the bubbling pressure is present.
 16. The flowpattern enhancer system of claim 1, wherein the gas velocity increasespromoting the atomization of liquids, with a relatively high gas flowvelocity of 4-6 m/s, achieving fog flow and a continuous flow structurehaving liquid droplets dispersed in the continuous gas phase.
 17. Theflow pattern enhancer system of claim 1, wherein the calculations foreach element design consider three different process: expansion,compression and mixing, and are performed through specific methodsconsisting primarily on determining the flow areas and geometriesthereof.
 18. The flow pattern enhancer system of claim 1, where the dragcoefficient is determined by the formula:Drag coefficient=Driving flow/Dragged flow.
 19. The flow patternenhancer system of claim 1, wherein said flow pattern enhancer systemincreased gas production over 300% from the initial production.
 20. Theflow pattern enhancer system of claim 1, wherein the flow patternenhancer system prevents formation of hydrates.
 21. The flow patternenhancer system of claim 1, wherein said flow pattern enhancer systemavoids the re-pressure of surface lines because of methane hydrateaccumulation.
 22. A method for enhancing the flow of a gas-producing oilwell with liquid load problems, which comprises passing a gas streamfrom the well in sequence through a) a primary expander; b) ahomogenization chamber, c) a secondary expander, and d) suction veinssuch that gas velocity increases to 4-6 m/s, achieving fog flow withliquid drops dispersed in the continuous gas phase.
 23. A gas-producingoil well pipe string arrangement having a flow pattern enhancer systemconnected in and communicating with the lower portion of said pipestring arrangement, said flow pattern enhancer system comprising thefollowing elements: a) primary expander; b) homogenization chamber, c)secondary expander, d) suction veins, and e) anchorage and tightnesssystem for displacing liquids accumulated at the bottom of the well tothe surface and extending the flowing life of the wells and increasingthe recovery factor.